Celadon is a glaze family rather than a colour swatch: a transparent or semi-transparent high-fired glaze coloured by a very small amount of iron, which reads green or blue-green in a reduction firing and yellow or amber in oxidation. It is the most famous glaze in ceramics and among the most sensitive to how the kiln is run.
Why the atmosphere decides the colour
Iron in a glaze takes different forms depending on how much oxygen is available at temperature. In a reduction firing, where the kiln is starved of oxygen, iron gives the cool green-blue that the tradition is named for. In an ordinary electric oxidation firing the same glaze goes amber or straw. Same recipe, same kiln temperature, entirely different pot.
How little iron is involved
Typically one or two percent, which is why celadons are transparent enough to show carving underneath. That transparency is the reason classical celadon ware is carved or incised: the glaze pools thicker in the cut lines and reads darker there, so the decoration is drawn by the glaze itself rather than painted on.
Celadon without a gas kiln
Commercial celadon-style glazes formulated for oxidation exist and give a convincing green in an electric kiln, using other colourants to reach a similar place. Purists distinguish them from true reduction celadons; buyers usually cannot. If the colour matters more than the chemistry, the oxidation versions are the practical route and suppliers stock them.
Getting it consistent
Celadon rewards thickness control more than most glazes because it is transparent: thin reads pale and washed out, thick reads deep and can craze. Dip a test tile once, twice and three times, fire it in your own kiln, and use whichever matches the intention. Keep the tile, because the difference between a good celadon and a disappointing one is usually a second in the bucket.
Questions people ask about celadon
What is celadon?
A high-fired transparent glaze coloured by a small amount of iron, giving green to blue-green in reduction and amber in oxidation.
Can I get celadon in an electric kiln?
Not a true reduction celadon, but commercial oxidation glazes reach a similar green using other colourants.
Why is celadon usually on carved pots?
Because it is transparent and pools in the carved lines, so the decoration is drawn by the glaze thickness itself.